Infectious agent's influence on serum procalcitonin concentration in patients with sepsis.

Abstract Theoretical background: Procalcitonin (PCT) is diagnostic and prognostic biomarker of sepsis. The objective of this study was to evaluate the correlation between sepsis causative agent and serum PCT concentration, since it would influence the initial empirical antimicrobial therapy selection. Methods: This retrospective study included 96 patients with sepsis who were admitted to Intensive Care Unit of Department of Infectious Diseases and Febrile Illnesses of University Clinical Center Ljubljana from September of 2011 through March of 2013. Sepsis was established clinically and defined aetiologically by haemoculture growth. Statistical evaluation was conducted in 76 patients who had not received proper antimicrobial therapy prior to blood collection. For PCT determination imunoluminometric method was used and concentrations above 5 mg/L were considered elevated. Results: Serum PCT concentration was significantly higher in Gram-negative sepsis (PCT median was 26,3 μg/L ) compared to Gram-positive sepsis (PCT median was 11,2 μg/L ) (p = 0,016). Differences in PCT concentrations between Gram-positive pathogens were not statistically significant (p = 0,09), however, S. aureus sepsis is linked to higher serum PCT concentration ( median PCT 12,8 μg/L ) than all other Gram-positive agents put together (median PCT of 5,9  μg/L ) (p = 0,016). Difference in PCT concentration in E. coli sepsis (median PCT of 38,2 μg/L ) compared to other enterobacteria (median PCT of 26,3 μg/L ) is not statistically significant (p = 0,902). Conclusions: Causative agent has a significant effect on serum PCT concentration in patients with sepsis. Higher values were present in Gram-negative than in Gram-positive sepsis. Amongst Gram-positive pathogens, S. aureus caused greater rise in PCT than other Gram-positive bacteria put together.